WO2017198172A1 - Power supply connection device, and charging-discharging control method for same - Google Patents

Abstract

Provided in the present invention is a power supply connection device, used to connect to a power generation unit and an energy storage unit, and supply power to a load. The power supply connection device comprises a current regulator, a DC converter, a dump load, an inverter, and a controller. The current regulator is used to regulate an input from the power generation unit. The DC converter is used to step up the voltage of an input from the energy storage unit, an input from the power generation unit, or the regulated input of the power generation unit. The dump load is used to release excessive energy. The inverter is used to perform DC to AC conversion. The power supply connection device further comprises a charging-discharging control device used to control the energy storage unit to charge or discharge. The controller controls the charging-discharging control device. Also provided in the present invention is a charging-discharging control method for a power supply connection device. By modifying a connection mode of an energy storage unit, the power supply connection device provided in the present invention reduces the number of times of charging and discharging the energy storage unit, thus increasing the service life of the energy storage unit, decreasing an operating cost of a micro-grid system comprising the power supply connection device, and ensuring stable and reliable power supply of the micro-grid system.

Description

Power supply access device and charging and discharging control method thereof

The present application claims priority to Chinese patent applications CN201610343620.4, CN201620472328.8, CN201610339975.6, and CN201620467454.4 on May 20, 2016. This application cites the entire text of the above-mentioned Chinese patent application.

Technical field

The present invention relates to the field of electrical control, and in particular to a power supply access device and a charging and discharging control method thereof.

Background technique

The rapid expansion of semiconductor power devices, the maturity of modern control theory, and the intelligent development of power systems have brought about an opportunity for the development of microgrid devices in microgrid systems.

In a typical smart microgrid system, in order to safely and efficiently access and make full use of distributed energy, including rectifiers, inverters, DC converters, unloaders and energy storage units, as shown in Figure 1, fans and photovoltaics The energy generated by the component is charged to the energy storage unit, and the energy storage unit discharges power to the DC or AC load.

With such a structure, during the power supply process of the microgrid, the energy storage unit is continuously charged and discharged, and the number of charge and discharge times of the energy storage unit is limited. After a period of use, the energy storage unit will be scrapped, and must be scrapped. Replacement makes the operating cost of the microgrid system higher.

In addition, the inverter, the DC converter and the unloader are each configured with a separate controller for control, and the devices in the system are relatively dispersed, so that the microgrid system occupies a large space and the operating cost is further improved.

Summary of the invention

In view of the problems in the prior art, the object of the present invention is to provide a power supply access device, which reduces the number of times of charging and discharging of the energy storage unit by changing the connection mode of the energy storage unit, thereby prolonging the use time of the energy storage unit. The operating cost of the microgrid system composed of the power supply access device is reduced, and the microgrid system is ensured to supply power stably and reliably.

The invention provides a power supply access device for accessing a power generation unit and an energy storage unit and supplying power to a load. The power supply access device comprises a rectifier, a DC converter, an unloader and an inverter, and the rectifier is used for the input of the power generation unit. The rectification, DC converter is used to input boost to the input of the energy storage unit, the input of the power generation unit or the rectified power generation unit, the unloader is used to release excess energy, the inverter is used to convert the direct current into alternating current, and the power supply access device further includes The charge and discharge control device and the controller are configured to control discharge or charging of the energy storage unit, and the controller controls the charge and discharge control device.

Further, the controller is connected to the DC converter, the unloader, and the inverter, and the controller is configured to control the DC converter, the unloader, and the inverter The unloader is connected to the DC converter and the inverter, and the unloader is mounted on a high voltage bus bar between the DC converter and the inverter.

Further, the charge and discharge control device is disposed between the energy storage unit and the high voltage bus.

Further, the DC converter is a BOOST boost circuit.

Further, the anode of the energy storage unit is connected to the charge and discharge control device through the inductance of the BOOST boost circuit, and then connected to the high voltage bus through the charge and discharge control device.

Further, the DC converter is a bidirectional BUCK-BOOST circuit.

Further, the anode of the energy storage unit is connected to the first end of the inductor of the bidirectional BUCK-BOOST circuit through the second controllable switch and the diode-connected diode parallel circuit, and the other end of the inductor is grounded, and the charge and discharge control device is connected. Between the first end of the inductor and the high voltage bus.

Further, the second controllable switch is used to control whether to access the energy storage unit.

Further, controlling whether to access the energy storage unit includes:

When the power of the electric power generated by the power generating unit is greater than the product of the load power and the first coefficient, if the energy storage unit is not full, the energy storage unit is charged; if the energy storage unit is full, cut Out of the energy storage unit, starting the unloader;

When the power of the electric power generated by the power generating unit is less than the product of the load power and the second coefficient, cutting into the energy storage unit, the energy storage unit is discharged, and the energy storage unit supplies power to the load together with the power generating unit. ;

When the power of the electric power generated by the power generating unit is greater than or equal to the product of the load power and the second coefficient and less than or equal to the product of the load power and the first coefficient, the energy storage unit is cut out.

Further, the charge and discharge control device includes a parallel unidirectional channel and a controllable channel. When the controllable channel is disconnected, the energy storage unit is discharged through the unidirectional channel, and when the controllable channel is turned on, the energy storage unit is charged through the controllable channel. .

Further, the controllable channel is provided with a first controllable switch, and the unidirectional channel is provided with a diode for unidirectional conduction.

Further, the power access device includes one or more sets of energy storage unit access terminals.

Further, the energy storage unit access terminal is configured to access an energy storage unit having the same charging and discharging characteristics.

Further, the energy storage unit access terminal is configured to access an energy storage unit with different charging and discharging characteristics, and the controller discharges the energy storage unit with different priorities or different frequencies.

Further, the controller has a battery management function.

Further, the battery management function includes:

Estimating the state of charge of the energy storage unit;

During the charging and discharging process of the energy storage unit, the terminal voltage, charging and discharging current are collected in real time.

Further, a plurality of or all of the rectifier, the DC converter, the unloader, and the inverter are disposed on the same PCB.

The invention also provides a charging and discharging control method for the above power supply access device, comprising the following steps:

(a) When the power generated by the power generating unit is greater than the product of the load power and the first coefficient, if the energy storage unit is not full, the control charges the energy storage unit; if the energy storage unit is full, the energy storage unit is cut out, and the energy storage unit is started. Charger

(b) when the power of the power generated by the power generating unit is less than the product of the load power and the second coefficient, the energy storage unit is controlled to discharge, and the energy storage unit supplies power to the load together with the power generating unit;

(c) When the power of the electric power generated by the power generating unit is greater than or equal to the product of the load power and the second coefficient and less than or equal to the product of the load power and the first coefficient, the energy storage unit is cut out.

Further, the first coefficient is greater than or equal to the second coefficient.

Compared with the prior art, the power supply access device and the charging and discharging control method thereof provided by the invention have the following beneficial effects: by changing the connection mode of the energy storage unit, the number of times of charging and discharging of the energy storage unit is reduced, thereby prolonging energy storage. The use time of the unit reduces the operating cost of the microgrid system composed of the power supply access device, and ensures the stable and reliable power supply of the microgrid system. Further, the rectifier, the DC converter, the unloader, and the inverter are disposed by the DC converter, the unloader, and the inverter sharing controller and on the same PCB board Multiple or all of the devices further reduce redundant components, reducing space and reducing costs.

DRAWINGS

1 is a schematic structural view of a power supply access device in the prior art;

2 is a schematic structural diagram of a power supply access device according to an embodiment of the present invention;

3 is a circuit diagram of a bidirectional BUCK-BOOST circuit and a charge and discharge control device;

4 is a circuit diagram of a BOOST boost circuit and a charge and discharge control device;

Figure 5 is another circuit diagram of the BOOST boost circuit and the charge and discharge control device;

FIG. 6 is a schematic structural diagram of a power supply access device according to still another embodiment of the present invention.

detailed description

As shown in FIG. 2, a power supply access device according to an embodiment of the present invention is configured to access a power generation unit and an energy storage unit and supply power to a load, and the power supply access device includes a rectifier, a DC converter, an unloader, and an inverter. And the controller, the rectifier is used for rectification of the input of the power generation unit, and the DC converter is used for inputting the input of the energy storage unit input, the input of the power generation unit or the rectified power generation unit, and the unloader is used for releasing more Residual energy, the inverter is used to convert direct current into alternating current, and the power supply access device further comprises a charge and discharge control device for controlling discharge or charging of the energy storage unit, and the controller controls the charge and discharge control device.

The power generating unit may be a direct current power generating device and/or an alternating current power generating device.

The power generation unit may be one or more.

In this embodiment, two power generating units are included, and the power generating unit includes a DC power generating device and an AC power generating device, wherein the DC power generating device is a photovoltaic component, and the AC power generating device is a fan. Of course, the AC power generating device may also be a diesel generator, and of course, may only include The fan, or only the photovoltaic, is not limited by the present invention.

In this embodiment, the energy storage unit is a lead acid battery. The energy storage unit may also be a battery such as a lead-acid battery, a lithium battery, a flow battery or a sodium-sulfur battery, which is not limited in the present invention.

The power supply access device further includes a controller connected to the DC converter, the unloader, and the inverter for controlling a DC converter, an unloader, an inverter, and charging and discharging Control device. The DC converter, the unloader, the inverter and the charge and discharge control device share one controller, which can reduce redundant devices and reduce costs.

The charge and discharge control device is disposed between the energy storage unit and the high voltage bus.

The unloader is connected to the DC converter and the inverter, and the unloader is mounted on a high voltage bus bar between the DC converter and the inverter.

A plurality or all of the rectifier, the DC converter, the unloader, and the inverter are disposed on the same PCB board, thereby achieving the beneficial effects of reducing space and reducing cost.

In this embodiment, a circuit is shown in FIG. 3, the DC converter is a bidirectional BUCK-BOOST circuit, and the anode of the energy storage unit is connected to the bidirectional BUCK through a parallel circuit between the second controllable switch Q2 and the diode D2 of the single conduction. a first end of the inductance L of the BOOST circuit, and the other end of the inductor L is grounded; a charge and discharge control device including a first controllable switch Q1 and a diode D1 of a single conduction, connected to the first end of the inductor L and the high voltage bus between.

The charging and discharging control device comprises a parallel unidirectional channel and a controllable channel. When the controllable channel is disconnected, the energy storage unit discharges through the unidirectional channel, that is, outputs power to the load; when the controllable channel is turned on, the storage is performed. The energy unit is charged through the controllable channel.

Specifically, the controllable channel is provided with a first controllable switch Q1, the unidirectional channel is provided with a diode D1 for unidirectional conduction, and the controller controls the opening and conducting of the first controllable switch Q1 through the control terminal A.

The charging and discharging control method of the power supply access device in this embodiment includes the following steps:

(a) When the power generated by the power generating unit is greater than the product of the load power and the first coefficient, if the energy storage unit is not full, the control charges the energy storage unit; if the energy storage unit is full, the energy storage unit is cut out, and the energy storage unit is started. Charger

(b) when the power of the power generated by the power generating unit is less than the product of the load power and the second coefficient, the energy storage unit is controlled to discharge, and the energy storage unit supplies power to the load together with the power generating unit;

(c) When the power of the electric power generated by the power generating unit is greater than or equal to the product of the load power and the second coefficient and less than or equal to the product of the load power and the first coefficient, the energy storage unit is cut out.

The second controllable switch Q2 is used to control whether to access the energy storage unit. The specific control process is as follows:

(1) When P _IN >φ ₁ P _OUT , if the energy storage unit is full, cut off the energy storage unit, and start the unloader to release excess power; if the energy storage unit is not full, charge the energy storage unit;

Specifically, if the energy storage unit is full, the controller turns off the PWM signal of the control terminal A of the first controllable switch Q1, and simultaneously turns off the PWM of the control terminal B of the second controllable switch Q2, and the first controllable switch Q1 and the first The two controllable switches Q2 are all in the off state, and the energy storage unit is cut out to avoid overcharging of the energy storage unit to extend the service life of the energy storage unit;

If the energy storage unit is not full, the controller turns on the PWM signal of the control terminal A of the first controllable switch Q1, and turns off the PWM of the control terminal B of the second controllable switch Q2, and the first controllable switch Q1 is in an on state. The second controllable switch Q2 is in an off state, and the electric power generated by the power generating unit is input to the high voltage bus, and the high voltage bus is charged to the energy storage unit;

(2) When φ ₂ P _OUT ≤ P _IN ≤ φ ₁ P _OUT , the energy storage unit is cut out, and only the power generation unit supplies power to the load to achieve power balance, reducing the number of times of charging and discharging the energy storage unit, thereby prolonging the storage. The service life of the unit;

Specifically, the controller turns off the PWM signal of the control terminal A of the first controllable switch Q1, and turns off the PWM of the control terminal B of the second controllable switch Q2. The first controllable switch Q1 and the second controllable switch Q2 are both at Disconnected state, cut out the energy storage unit;

(3) When P _IN <φ ₂ P _OUT , the energy storage unit is cut in, the energy storage unit is discharged, and the power supply unit is supplied with power to the load to achieve power balance;

Specifically, the controller turns off the PWM signal of the control terminal A of the first controllable switch Q1, and simultaneously turns on the PWM of the control terminal B of the second controllable switch Q2, the first controllable switch Q1 is in an off state, and the second The control switch Q2 is in an on state, and is cut into the energy storage unit;

Among them, P _IN is the power of the power generated by the power generation unit, and P _OUT is the load power. φ ₁ is the first coefficient, and φ 2 is the second coefficient, which may be the same or different.

When φ1 and φ2 are the same, for example, φ1=1, φ2=1, when P _{IN is} less than P _OUT , the energy storage unit discharges, and supplies power to the load together with the power generation unit; when P _IN is equal to P _OUT , the energy storage unit is cut out; When P _{IN is} greater than P _OUT , if the energy storage unit is full, cut off the energy storage unit to avoid overcharging the energy storage unit and prolong the service life of the energy storage unit. If the energy storage unit is not full, use excess power to the energy storage unit. Charging.

In order to avoid P _IN equal to frequent switching near P _OUT , that is, slightly smaller than P _OUT , the energy storage unit discharges slightly larger than P _OUT and cuts out the energy storage unit or charges the energy storage unit. Different φ ₁ and φ ₂ can be used. φ _{1 is} larger than φ ₂ such as φ ₁ =1.05, φ ₂ =1. When P _{IN is} less than P _OUT , the energy storage unit is discharged and supplies power to the load together with the power generation unit; when P _{IN is} greater than 1.05 times of P _OUT , Whether the energy unit is full or not, and P _{IN is} between 1.05 times P _OUT and P _OUT , and the energy storage unit is cut out, that is, the power and power of the power generated by the power generation unit are balanced.

In another embodiment, the circuit shown in FIG. 4 is adopted, the DC converter is a BOOST boost circuit, and the anode of the energy storage unit is connected to the charge and discharge control device through the inductance L of the BOOST boost circuit, and then controlled by charge and discharge. The device is connected to the high voltage bus. Specifically, the first controllable switch Q1 is connected in parallel with the diode D1 of the single conduction, and is connected between the inductor L and the high voltage bus.

The first controllable switch Q1 can use IGBT, MOS tube, if IGBT, MOS tube itself With a single-conducting diode, there is no need to set a single-way diode separately; however, if the current is large, a single-way diode can be set separately.

In another embodiment, a circuit as shown in FIG. 5 is used, the DC converter is a BOOST boost circuit, and the first controllable switch Q1 can employ a bidirectional thyristor.

In this embodiment, the power supply access device includes a group of energy storage unit access terminals. In another embodiment, as shown in FIG. 6, the power supply access device includes two sets of energy storage unit access terminals, and is capable of accessing two Group energy storage unit: battery 1 and battery 2, battery 1 and battery 2 respectively control charging and discharging through charging and discharging control device. When the power difference between the load and the power generated by the power generating unit is large, two groups of battery discharging outputs can be used simultaneously. Power to ensure stable power supply to the power supply system; or when one battery is charging, use another battery to discharge output power.

Of course, the power supply access device may also include a group of energy storage unit access terminals, which is not limited by the present invention.

Using the power supply access device in this embodiment, multiple sets of energy storage unit access terminals can access energy storage units with the same or different charging and discharging characteristics, for example, all connected to lead-acid batteries; or can be respectively connected to lead-acid batteries and Lithium batteries, in which lithium batteries are more suitable for frequent charge and discharge, so in the power supply process, the lithium battery is preferred; or the lead acid battery and the lithium battery are discharged at different frequencies.

The battery management system (BMS) is mainly to improve battery utilization, prevent overcharging and overdischarging of the battery, extend battery life, and monitor battery status.

In this embodiment, the controller implements the following functions of the BMS:

(1) Estimating the state of charge (SOC) of the energy storage unit, that is, the remaining power of the energy storage unit, ensuring that the SOC is maintained within a reasonable range, thereby preventing the energy storage unit from being overcharged or overdischarged. Causing damage;

(2) During the charging and discharging process of the energy storage unit, the terminal voltage, charging and discharging current are collected in real time to prevent overcharging or overdischarging of the battery.

The controller implements the BMS function, which can effectively save 3% of the battery life, thereby reducing the cost of the overall equipment.

The above has described in detail the preferred embodiments of the invention. It will be appreciated that many modifications and variations can be made in the present invention without departing from the scope of the invention. Therefore, any technical solution that can be obtained by a person skilled in the art based on the prior art based on the prior art by logic analysis, reasoning or limited experimentation should be within the scope of protection determined by the claims.

Claims (19)

A power supply access device is configured to access a power generating unit and an energy storage unit and supply power to a load, the power supply access device comprising a rectifier, a DC converter, an unloader and an inverter, wherein the rectifier is used for a power generation unit Input rectification, the DC converter is used to input boost to an energy storage unit input, a power generation unit input or a rectified power generation unit, the unloader is for releasing excess energy, and the inverter is used to convert direct current into alternating current The power supply access device further includes a charge and discharge control device and a controller, the charge and discharge control device is configured to control discharge or charging of the energy storage unit, and the controller controls the charge and discharge control device. The power supply access device according to claim 1, wherein said controller is connected to said DC converter, said unloader, and said inverter, said controller for controlling said DC conversion The unloader and the inverter, the unloader is connected to the DC converter and the inverter, and the unloader is mounted on the DC converter and the inverse The high voltage bus between the transformers. The power supply access device according to claim 1 or 2, wherein the charge and discharge control device is disposed between the energy storage unit and the high voltage bus. The power supply access device of claim 3 wherein said DC converter is a BOOST boost circuit. The power supply access device according to claim 4, wherein the anode of the energy storage unit is connected to the charge and discharge control device through the inductance of the BOOST boost circuit, and is connected to the high voltage bus through the charge and discharge control device. The power supply access device of claim 3 wherein said DC converter is a bidirectional BUCK-BOOST circuit. The power supply access device according to claim 6, wherein the positive pole of the energy storage unit is connected to the first inductance of the bidirectional BUCK-BOOST circuit through a second controllable switch and a diode-connected diode parallel circuit. End, the other end of the inductor is grounded, charge and discharge control device Connected between the first end of the inductor and the high voltage bus. The power supply access device of claim 7, wherein the second controllable switch is configured to control whether the energy storage unit is connected. The power supply access device of claim 8, wherein controlling whether to access the energy storage unit comprises: And when the power of the power generated by the power generating unit is greater than a product of the load power and the first coefficient, if the energy storage unit is not full, charging the energy storage unit; if the energy storage unit is full, cutting out the The energy storage unit starts the unloader; When the power of the electric power generated by the power generating unit is less than the product of the load power and the second coefficient, cutting into the energy storage unit, the energy storage unit is discharged, and the energy storage unit supplies power to the load together with the power generating unit. ; When the power of the electric power generated by the power generating unit is greater than or equal to the product of the load power and the second coefficient and less than or equal to the product of the load power and the first coefficient, the energy storage unit is cut out. The power supply access device according to at least one of claims 1 to 9, wherein the charge and discharge control device comprises a parallel unidirectional channel and a controllable channel, wherein when the controllable channel is disconnected, the storage The energy unit discharges through the one-way channel, and when the controllable channel is turned on, the energy storage unit is charged through the controllable channel. The power supply access device of claim 10, wherein the controllable channel is provided with a first controllable switch, the one-way channel being provided with a diode for unidirectional conduction. The power supply access device according to at least one of claims 1 to 11, wherein the power supply access device comprises one or more sets of energy storage unit access terminals. The power supply access device according to claim 12, wherein the energy storage unit access terminal is configured to access an energy storage unit having the same charging and discharging characteristics. The power supply access device according to claim 12, wherein the energy storage unit access terminal is configured to access energy storage units having different charging and discharging characteristics, and the controllers have different priorities or different The frequency discharges the energy storage unit. A power supply access device according to at least one of claims 1 to 14, wherein the controller has a battery management function. The power supply access device of claim 15 wherein said battery management function comprises: Estimating the state of charge of the energy storage unit; During the charging and discharging process of the energy storage unit, the terminal voltage, charging and discharging current are collected in real time. A power supply access apparatus according to at least one of claims 1 to 16, wherein a plurality or all of the rectifier, the DC converter, the unloader, and the inverter are set On the same PCB board. A charging and discharging control method for a power supply access device according to at least one of claims 1 to 17, comprising the steps of: (a) when the power of the power generated by the power generating unit is greater than the product of the load power and the first coefficient, if the energy storage unit is not full, control is charged to the energy storage unit; if the energy storage unit is full, cut out The energy storage unit starts the unloader; (b) controlling the discharge of the energy storage unit when the power of the power generated by the power generation unit is less than a product of the load power and the second coefficient, and the energy storage unit supplies power to the load together with the power generation unit; (c) when the power of the electric power generated by the power generating unit is greater than or equal to the product of the load power and the second coefficient and less than or equal to the product of the load power and the first coefficient, the energy storage unit is cut out. A charging and discharging control method for a power supply access device according to claim 18, wherein said first coefficient is greater than or equal to said second coefficient.

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